I haven't read the story, but I wonder if it's not generational Most of these people are young, and when you're young you a) mostly don't have any interest in romance and sex among older people, and Simon at least is clearly older by their lights b) tend to respond in a certain way to older people who can be considered in some way powerful. I mean, they identify with the singers, and from that point of view Simon is an intimidating authority figure and Ryan's role is somewhat manipulative.

It was funny even for me, doing a high school AU, in that some of the casting seemed foreordained- Simon HAD to be dean of discipline. Obviously I wanted him to be a nuanced character, but I'm also, you know, old now, and send people to the office myself.